Method and apparatus for forming metal



Oct. 9, 1962 D. D. SETSER METHOD AND APPARATUS FOR FORMING METAL Filed June 5. 1960 r (J R. e \w T 5. x 0 M .3 mm Qm d a I. a & g 3 m W A an vw 0 6 w mv I B QN) %N\ WM MN w Wm] wv J EM mbxx h wm Q mv g Qw wm mw S 5339b;

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United States Patent ()fiice 3,057,313 Patented Oct. 9, 1962 3,057,313 NLETHOD AND APPARATUS FOR FORMING METAL Donald D. Setser, Tulsa, Okla, assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed June 3, 1960, Ser. No. 33,693 5 Claims. (Cl. 113-44) This invention relates to the art of metal forming, and particularly to the forming of metal articles from suitable blanks which are suddenly subjected to high pressures.

It is known to achieve die forming of metal articles by using explosives to drive fluid against the metal to be formed and drawing the metal against an adjacent die. However, the use of explosives in such operations is relatively expensive and may represent a safety hazard.

Accordingly, a principal object of this invention is to provide an improved apparatus for forming metal objects against a die.

Another object of this invention is to provide an improved, economical, and safe apparatus and method for use in forming metal articles against a die surface.

In accordance with this invention, there is provided a die enclosure having means for holding an element or blank to be formed and means for evacuating the enclosure. The die enclosure is coupled to a liquid column and separated therefrom by a frangible sealing member. Means are provided for pressurizing the liquid column to break the frangible member, and directing the resulting high velocity liquid of the column at the member to formed.

The invention, as well as additional objects and advantages thereof, will best be understood when the following detailed description is read in connection with the accompanying drawing, in which the single FIGURE shows, in diagrammatical form, apparatus in accordance with this invention.

Referring to the drawing, there is shown a multiple section cavity mold, indicated generally by the numeral 10. The mold includes two mating sections 12, 14, which are clamped together along a parting line in a fluid-tight relationship as at 16. The section 12 includes a cavity wall 18 and has a bore 20 extending through the mold wall and communicating with the cavity. A frangible disc seal 22 is held in place at the cavity end of the bore 29 by an annular retaining ring 24.

The section 14 of the mold 10 comprises a cavity part 26 having a die 28 disposed opposite to the bore 20 of the section 12. As a blank, a sheet 30 of metal to be formed against the die 28 is disposed in the section 14, being retained by any suitable means such as small ridges 32.

A bore 34 extends through the wall of the section 14 and is coupled by mean-s of a tube 36 and valve 38 to a vacuum pump 40. A vent valve 68 is also coupled to the tube 36.

A pressure reservoir 42 having a vent valve 70 is coupled to the bore 20 through a tube 44 and valve 46. A small bore 48, whose inner end is surrounded by a screen 49, extends through the lower Wall of the section 12 and is coupled through tube 50, valve 52, pump 54 and check valve 56 to the reservoir 42. A gas source 58 (which may be a tank of high pressure gas or, in simple form, atomspheric gas) is coupled by means of tubing 60 through a pump 62 and valve 64 to the pressure reservoir 42.

In operation, with the valves 46, 68, and 52 closed, the mold is opened along parting line 15 and a sheet 30 of metal to be formed is placed in the mold section 14 adjacent to the die 28. A frangible element 22 is inserted against the inner end of the bore 20 and is sealed in place by the threaded retainer element 24. The mold sections are then sealed together by clamping them (as at 16). The valve 38 is then opened and the pump 40 actuated to evacuate the interior or cavity of the mold. Upon being suitably evacuated, the pump 40 is stopped and the valve 38 closed.

The valves 46 and 64 are opened and pump 62 actuated to place the liquid in the reservoir 42 under additional pressure.

When the liquid 66 is under sufiicient pressure, the frangible element 22 bursts and the highly pressurized liquid in 42 rushes into the mold cavity and impinges on the metal sheet 30 with very high impact forces, forcing the sheet 30 against the die and permanently forming it.

The valve 46 is then closed, the vent valves 68 and 70 and valve 52 opened, and the pump 54 operated to drain the mold cavity of fluid 66 and return the fluid to the reservoir 42. When the cavity of the mold 10 has been drained, the mold is opened, the formed article removed, and a new sheet 30 inserted. The debris of the frangible disc is removed from the cavity 26 and a new frangible disc seal 22 secured in place.

The valve 52, 68 and 70 are then closed (as is valve 46), the valve 38 is opened, the mold cavity evacuated, and the forming operation repeated as before.

It is obvious that a source of highly compressed gas may be substituted for the pump 62 in the apparatus of the invention. If the liquid is a cheap liquid such as water, the tube 50, valves 52 and 56 and pump 54 may be dispensed with as there is little need to recycle the liquid except as an economy measure. In such a situation means for replenishing the supply of liquid to the reservoir 42 are provided.

Examples of frangible discs are a ceramic such as glass or rigid plastic elements such as polystyrene, for example. It is preferable that the discs be stressed at the time of manufacture to promote their shattering into small pieces on being ruptured.

Water or petroleum oil are examples of common liquids which may be used in practicing this invention.

Gases which may be used for pressurizing the liquid column include gases which are either soluble or insoluble in the liquid column. Compressed air or nitrogen are examples of such suitable gases, although other gases may be used.

What is claimed is:

l. A method of forming metal articles by pressing a sheet of metal against a die, comprising placing said metal sheet adjacent to a die in a mold cavity having a frangible seal therein, evacuating said cavity, pressurizing a liquid mass which is contiguous to said frangible seal, subjecting said seal to fluid pressure to rupture said seal, and impinging said compressed pressurized liquid against said sheet to force the sheet against said die.

2. Apparatus for forming metal articles, comprising a mold including a cavity enclosed by a wall, said cavity having a die therein, means adjacent to said die for positioning a sheet to be formed, means including a valve for evacuating said cavity, a bore, said bore extending through said wall and opening directly towards said die, the bore being sealed by a frangible member, said member being capable of withstanding a predetermined pressure differential across itself, a liquid reservoir, said liquid reservoir being disposed outside of said cavity, blow means, said blow means being coupled between said reservoir and coupled to said bore, and means to pressurize 5 said reservoir.

3. Apparatus in accordance with claim 2, wherein said frangible membe is replaceable.

4. Apparatus in accordance with claim 2, wherein means 39 are provided for recycling liquid from said cavity to 10 2,847,957 said liquid reservoir.

5. Apparatus in accordance with claim 2, wherein said frangible member is ceramic.

References Cited in the file of this patent UNITED STATES PATENTS Middler Apr. 21, 1936 Cecil Apr. 15, 1958 Watter et al Aug. 19, 1958 

